Donatas Montiejunas led Houston with 16 points off the bench. Omer Asik added 13 points and 11 rebounds.
San Antonio used a 13-1 run to open up an 86-71 lead with 11:26 remaining. Witherspoon had seven points during the run.
Toronto fans have nothing to cheer for in Game 5.
Take a behind-the-scenes look at the Thunder's dominating Game 4 performance against the Warriors.
LeBron James gets a steal and goes to the other end for the soaring two-handed slam dunk.